Although previous work has shown that, in the rhesus monkey eye, transport of the organic anions p-aminohippurate and cholic acid occurs in the iris and that this parallels ciliary body transport mechanisms, much remains to be learned about these three systems. It is proposed to extend these findings in the following ways: I. Prostaglandin transport will be studied by incubations in vitro of iris and ciliary body specimens with radio labeled prostaglandins to define the nature of an independent iris system; II. An autoradiographic study is planned to locate the anatomic site of these transport phenomena, and III. A membrane preparation in vitro will be used to determine the direction of the transport. Based on the findings and techniques used above, the effects of several drugs, including corticosteroids and pilocarpine, will be studied in both ciliary body and iris specimens. Finally, in order to be able in the future to utilize human iridectomy specimens to study anion transport phenomena, a pilot tissue culture project has been undertaken using iris pigment epithelium; and continuation of this study is proposed.